© 2015 Electric Power Research Institute, Inc. All rights reserved.

Renewable Generation Hosting Capacity

Screening Tool for a Transmission Network

Vikas Singhvi Deepak Ramasubramanian

1st International Conference on Large-Scale Integration of Renewable Energy in

India

New Delhi 6-8th September, 2017

2 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Renewable Generation/DER Hosting Capacity Tool for a Transmission Network

Goal : Develop a automated tool/engine for transmission system – Provides maximum renewable

generation/DER a transmission region can host without any network upgrades

– High-level screening tool

Disclaimer – The tool is not intended to replace detail

feasibility and system impact studies which are imperative to make to any investment decisions

The tool will help planners :

• To screen through multiple interconnection requests allowing for a better understanding of where and how much new generation resources would impact the system

• To identify optimal versus non-optimal locations of future renewable generation/DER deployments such that grid updates can be minimized

Tool: Framework

Input

Analysis

Criteria

Phase 1

Generation Dispatch

Load Levels

Injection Nodes

Network Conditions

Power Flow Analysis

Simple Short Circuit Analysis

Thermal Limtis Voltage LimitsShort-circuit Ratio(SCR)

Stability Analysis

(Small-signal and Transient)

Stability Limits

Renewable Temporal Variations

Renewable Functional Controls

Any Limit Violated

As-is Renewable Hosting Capacity of the Zone/Region/Area

Phase 2

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Tool Design: Overview

Study Case Developement Layer

- Compilation of user inputs

- Development of Power Flow test cases

- Building a case repository

Analysis Layer

- Power flow studies

- Short circuit calculations

- Limit violation assessments (voltage limits, line thermal limits, and short circuit ratio)

Output Compilation Layer

- Compiles analysis results for each of the test cases

- Enables capabilities such as post-processing of analysis results, visualizations, report/log creation

5 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Flow Diagram: Case Definition Layer

• For example; with 2 load levels, 10 contingencies and 2 location sets of renewable, the total number of generated cases will be (2x10x2) = 40

• Also, 4 cases will be generated by adding renewables/ DERs in the 2 load at the 2 specified location sets, making the total number of cases 44 in the process.

Start

Base cases to include in the study

(PSSE power flow .sav files)

User Input

PSSE Working Power Flow Case

Implementation of Critical Network Contingency Set

Incremental sav cases generated using ACCC (*con file)

User Input

Add Wind/PV/DER (Initialize with 0

MW)

Model parameters for Wind/ PV/DERs

User Input

POI Locatios [ .xlsx / .xls files ]

User Input

Generated .sav Cases

Provided by utility or developed using Production-cost

model

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Flow Diagram: Analysis Layer Generated power flow cases from Case Definition Layer

PSSE Working Case

Power Flow Converged?

Subroutine: attempt to make

the case converge

Limits Violated?

Previous penetration level is set as the maximum hosting capacity

for the current working case

All cases analyzed?

Stop / Exit

Update Case Identifier

Run Power Flow and Check Convergence

• Conventional Generation Re-dispatch

• Short-Circuit Calculations and Short-Circuit Ratio (SCR) Limit Check

• Increment Renewable and DER generations

Power Flow Converged?

Skip the case

Bus Voltage and Line Thermal Limit Check

Yes

Yes

Yes

No

No

No

No

Yes

7 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Implementation of the Short-Circuit Limit Assessment Block

• SCMVA = short-circuit MVA contributed by the synchronous generator

• SCRlimit = 10 (or any user defined value )

• PRated = Rated MW of the Renewable or DER Plant to be connected

Condition:

Implement Conventional Generation Re-dispatch based on the re-dispatch scheme (without solving PF)

Calculate Short Circuit MVA at the candidate buses

Rank the candidate POI buses according to their SCMVA

Define total increment in Renewable / DER generations and allocate the increment among the candidate buses based

on their SCMVA ranking

Condition check?

Calculate SCR

Implement generation increment PSSE power flow case

𝑆𝑆𝑆𝑆𝑀𝑀𝑀𝑀𝑀𝑀𝑆𝑆𝑆𝑆𝑆𝑆𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙

> 𝑃𝑃𝑅𝑅𝑅𝑅𝑙𝑙𝑅𝑅𝑅𝑅 Re-allocate the excess generations at constrained buses in accordance with

the bus rankings based on SCMVA

Re-allocation successful?

STOP: • Calculate the amount that couldn’t be re-allocated. • Adjust re-dispatch by that amount • Set the current amount of penetration as the MAX for this case

NOT Satisfied

Satisfied

NO

YES

Power Flow convergence, voltage and line thermal limit check

8 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Tool Implementation: Overview of the GUI

Hosting Capacity v/s region, re-dispatch,etc….

Tool Main Window

9 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Tool Implementation: Overview of the GUI Tool Main Window

10 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Tool Output : Sample Results

Maximum Penetration Level across Multiple Contingency Cases

Maximum Penetration Level Split up by Type of Generation Resource

Branch Flow Violations v/s Generation Level

Voltage magnitude Violations v/s Generation Level

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Data Requirements

Common data for all types of screening studies: – Transmission planning model ( Peak, off-peak, etc) – Contingency list (.con file) and .sub/.mon files – Thermal/Voltage criteria

Data for renewable generation/DER limit assessment : – Potential buses for future renewable generation and DER

deployments in a region – Generator re-dispatch scheme(s) priority order

12 © 2015 Electric Power Research Institute, Inc. All rights reserved.

Next Steps Test and validate the tool across multiple utility cases

Develop additional automated screening capabilities :

– Impact/limits on generation retirement/new generation injection (Eg. Gas)

– Impact/limits on increase in load withdrawal

Explore feasibility of adding other criteria : Small signal stability Transient Stability FIDVR

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Together…Shaping the Future of Electricity